I am tracking a website which is available under two domains (with and without a “www.” prefix). Currently the longer one redirects to the shorter one.

However, it seems that the longer one was used when creating the account, and things like in-page analytics fail with an error:

Error: The Website in your settings (http://www.example.com),
redirects into a different domain. (http://example.com). In-Page
Analytics currently works on only one domain. Note that
www.example.com and example.com are NOT considered to be on the same
domain. Also, make sure you're not redirecting from http:// to
https:// or vice versa.

So, I inferred I should probably update the URL inside the Analytics. I found that the URL is editable in at least two places:

“Property Settings” tab on a property list page (the one which lists profiles)

“Profile Settings” tab on a profile page (one where there are tabs like “Assets”, “Users”, “Goals” and so on…)

Questions: Which one should I change? What will happen to already harvested data, will they be preserved?